European Patent Application No. 0 661 446 descibes a fuel injection valve with an integrated spark plug for direct injection of fuel into a combustion chamber of an internal combustion engine and igniting the fuel injected into the combustion chamber. The fuel injection valve includes a valve body having a valve opening surrounded by a valve seat on the spray outlet end and sealed by a valve closing body when the solenoid is not energized, the closing body being is arranged on a valve needle extending through the interior of the valve body. The valve needle can be operated electromagnetically by means of a solenoid acting on an armature to open the fuel injection valve. The valve seat and the valve closing body are arranged on the inside of the valve opening on the inlet end, and the valve body is shaped on the spray outlet end into a central starting electrode surrounded by a pot-type counter-electrode. High voltage is supplied from the end of the fuel injection valve opposite the spray outlet end to the central starting electrode over the valve body, the valve needle and an axial extension which is connected to the valve needle over a restoring spring. The armature surrounds the inlet end of the valve needle in a ring and is insulated from the valve needle by an insulation body. Fuel is delivered through an outer ring channel opening into the inlet end of the valve body.
A disadvantage of this conventional fuel injection valve with an integrated spark plug is that the insulation body arranged between the armature and the valve body is exposed to tensile stress when the fuel injection valve is opened, and therefore a corresponding form-fitting connection between the armature and the insulation body on the one hand and the insulation body and the valve needle on the other hand must be provided.
Furthermore, the insulation body has a relatively complex shape in order to surround the valve needle and the restoring spring on all sides outside the valve body to insulate them. Since ceramic materials, which are relatively brittle and therefore are difficult to process, are generally used for high-voltage insulation, it is relatively expensive to produce the relatively complex shape of the insulation body provided between the armature and the valve needle and the other insulation body needed for high-voltage insulation. Furthermore, ceramic materials have a tendency to show premature fatigue when exposed to tensile stress for extended periods.
Another fuel injection valve with an integrated spark plug is described in European Patent Application No. 0 632 198. With this conventional fuel injection valve, electric insulation is not provided between the valve needle and the armature connected to the valve needle or between the armature and a magnet core that is opposite the armature and can be energized by a solenoid. Instead, an insulation body arranged between the valve body and the casing is lengthened so that it surrounds the magnet core radially toward the solenoid and thus prevents a high-voltage sparkover to the solenoid. However, this design does not permit the development of a closed magnetic flux circuit of ferromagnetic material. Therefore, relatively high solenoid currents are needed to operate the fuel injection valve to adequately magnetize the magnet core passing through the solenoid.